a volatile matter arising from wood and other fuel along with the smoke; or rather, it is the smoke itself condensed and gathered to the sides of the chimney. Tho' once volatile, however, foot cannot be again resolved into vapour; but, if distilled by a strong fire, yields a volatile alkali and empiryeumatic oil, a considerable quantity of fixed matter remaining at the bottom of the distilling vessel. If burnt in an open fire, it flames with a thick smoke, whence other foot is produced. It is used as a material for making sal ammoniac, and as a manure. See Chemistry, no 796.; and Agriculture, no 20.

Scot-Black. See Colour-Making.